The invention concerns the field of wireless networks, made up of a plurality of entities intercommunicating, for example by radio channel.
More specifically, the invention relates to a method of adjusting the sending power—also called the transmitting power—of the network entities. It also relates to a wireless communication unit intended to form an entity of such a network.
The invention applies particularly to ad hoc networks, i.e. networks that do not have a pre-existing infrastructure for sending data from one entity to another.
It should be remembered that, in the field of radio waves, any signal transmitted by a sending entity to a destination entity is subject to an attenuation proportional to a power of the distance separating these entities (in practice, this power is between 2 and 6).
That is why the transmitting power of the sending entity must be sufficient for the signal effectively to reach the destination entity.
It is not, however necessary for the signal to reach the destination entity directly (this case being referred to as direct sending): it can, in practice, pass through a third party entity of the network, called an “intermediate node” or “routing node” (this case being referred to as indirect sending).
It should be noted that, in an ad hoc network, each entity can alternately serve as sending entity, destination entity or intermediate node.
In order to provide network connectivity, that is, ensure that, whatever the sending and destination entities, there is always a path enabling the message to be delivered to the receiving entity from the sending entity, it is necessary for each sending entity of the network to know the location of its adjacent entities, and vice versa.
An adjacent entity of a sending entity is any entity, for which the sending entity is near enough to receive a direct signal.
Each sending entity of the network has a corresponding sending zone, the radius of which is a function of the transmitting power of that entity.
Numerous communication protocols, with little regard for energy saving, allow for the transmitting power of any sending entity to be set in all cases to its maximum value.
While such protocols generally provide network connectivity, they do, however, involve a high energy consumption, which is detrimental to the autonomy of each entity of the network.
In the interests of energy saving, for the purpose of increasing the autonomy of the entities, it is therefore desirable to reduce the transmitting power of the network entities as much as possible while maintaining the connectivity of the network.
There are communication protocols that propose to modulate the transmitting power of a given entity according to the topology of its vicinity (see, for example, the International Patent Application published under the number WO 02/03567).
However, the protocol employed is relatively complicated and requires memories and complex algorithms which put a strain on the costs and hamper the operation of the network.
The invention seeks in particular to resolve the abovementioned drawbacks by proposing, among other subjects, a method of adjusting the transmitting power of a sending entity in a wireless communication network enabling the energy consumption within the network to be limited simply and effectively, while ensuring the connectivity of the network.